Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 030625
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
825 PM HST MON MAY 2 2016

.SYNOPSIS...
BREEZY TRADE WINDS WILL PERSIST ACROSS THE ISLAND CHAIN INTO
WEDNESDAY. LOW CLOUDS AND SHOWERS CARRIED BY THE TRADES WILL
FAVOR WINDWARD AND MAUKA SECTIONS...WITH AN INCREASE IN TRADE
SHOWERS EXPECTED STARTING TUESDAY NIGHT. A LATE SEASON FRONT
APPROACHING KAUAI FROM THE NORTHWEST THURSDAY AND FRIDAY...WILL
CAUSE WINDS ACROSS THE STATE TO WEAKEN AND VEER FROM THE
SOUTHEAST. THIS WILL ALLOW LOCAL AFTERNOON SEA BREEZES AND
NIGHTTIME LAND BREEZES TO DEVELOP BY THE END OF THE WORK WEEK.
THE FRONT IS EXPECTED TO STALL AND EVENTUALLY DISSIPATE NEAR
KAUAI LATER THIS WEEK. TRADE WINDS MAY GRADUALLY RETURN TO THE
ISLAND CHAIN THIS WEEKEND.

&&

.DISCUSSION...
A 1032 MB SURFACE HIGH NEAR 36N 151W HAS A SURFACE RIDGE EXTENDING
SOUTHWEST THROUGH A POINT MORE THAN 800 MILES NORTH OF LIHUE. THE
PRESSURE GRADIENT SOUTH OF THESE FEATURES IS MAINTAIN BREEZY TRADE
WINDS ACROSS THE ALOHA STATE EARLY THIS EVENING. MID-LEVEL
RIDGING IN THE VICINITY OF THE ISLANDS IS MAINTAINING STABLE
ATMOSPHERIC CONDITIONS ACROSS THE ISLAND CHAIN. SATELLITE IMAGERY
AND RADAR REFLECTIVITY DATA SHOW SCATTERED TO LOCALLY BROKEN LOW
CLOUDS AND ISOLATED SHOWERS STREAMING TOWARD KAUAI THIS EVENING.
THERE ARE ALSO LOW CLOUDS ALONG THE WINDWARD SIDES OF MOST
ISLANDS. LOW CLOUDS ARE DISSIPATING OVER THE LOWER ELEVATIONS OF
THE LEEWARD BIG ISLAND AS NIGHTTIME COOLING IS CAUSING DRAINAGE
FLOW TO SET UP THERE. OTHERWISE...THERE ARE FEW CLOUDS AND MAINLY
DRY CONDITIONS ACROSS THE LEEWARD SECTIONS OF THE SMALLER ISLANDS.

ELSEWHERE...THE RAGGED LEADING EDGE OF A NEARLY 100 MILE WIDE
BAND OF BROKEN LOW CLOUDS AND SCATTERED SHOWERS ASSOCIATED WITH A
DECAYING FRONT IS ABOUT 165 MILES NORTH OF HONOLULU. THIS LEADING
EDGE IS ADVANCING SLOWLY SOUTHWARD. LOW CLOUDS AND SHOWERS AHEAD
OF THIS DIFFUSE LEADING EDGE ARE EXPECTED TO BECOME MORE PREVALENT
LATER TONIGHT OVER WINDWARD KAUAI AND OAHU AS INCREASING MOISTURE
MOVES IN FROM THE NORTH.

AS THE SURFACE HIGH FAR NORTH-NORTHEAST OF THE STATE MOVES SLOWLY
EASTWARD OVER THE NEXT FEW DAYS...EXPECT THE BREEZY TRADE WINDS TO
PERSIST. THE LOW LEVEL TRADE WIND FLOW WILL CONTINUE TO BRING LOW
CLOUDS AND SHOWERS MAINLY ALONG WINDWARD FACING SLOPES AND ACROSS
THE HIGHER TERRAIN. LEEWARD LOCATIONS OF THE SMALLER ISLANDS WILL
HAVE PARTLY CLOUDY SKIES WITH A FEW BRIEF SHOWERS. EXPECT CLOUDS
AND ISOLATED SHOWERS TO DEVELOP EACH AFTERNOON OVER THE KONA
SLOPES OF THE BIG ISLAND DURING THE NEXT FEW DAYS,

THE BAND OF ENHANCED LOW LEVEL MOISTURE ASSOCIATED WITH THE
DECAYING FRONT WILL CONTINUE TO MOVE TOWARD THE STATE DURING THE
NEXT 24 HOURS...WITH AN EXPECTED ARRIVAL TIME OF TUESDAY NIGHT.
THE MOISTURE ASSOCIATED WITH THIS FEATURE WILL LIKELY BRING
INCREASING CLOUD COVER AND SHOWERS TO WINDWARD AND MAUKA SECTIONS...
WITH SOME SHOWERS SPILLING OVER TO LEEWARD LOCATIONS ON THE
SMALLER ISLANDS.

THE FORECAST MODEL OUTPUT CONTINUES TO SHOW THE WINDS WEAKENING AND
VEERING OUT OF THE SOUTHEAST TOWARD THE END OF THE WORK WEEK AS A
COLD FRONT APPROACHES KAUAI FROM THE NORTHWEST. THIS FRONT WILL
LIKELY STALL NORTH OF KAUAI BY FRIDAY...BEFORE IT DISSIPATES THIS
WEEKEND. THE CURRENT FORECAST SHOWS THE TRANSITIONAL PERIOD AHEAD
OF THE FRONT STARTING WEDNESDAY NIGHT AND CONTINUING INTO EARLY
THURSDAY. THE WEAKER BACKGROUND FLOW IS EXPECTED TO ALLOW LOCAL
AFTERNOON SEA BREEZES AND NIGHTTIME LAND BREEZES TO DEVELOP OVER
LEEWARD AND INTERIOR SECTIONS OF THE ISLAND CHAIN THURSDAY AND
FRIDAY. THE CONVERGENCE OF LOCAL SEA BREEZES WILL LIKELY ALLOW
CLOUD BUILD UPS AND SCATTERED SHOWERS OVER LEEWARD AND INTERIOR
AREAS. NORTHEASTERLY TRADE WINDS ARE EXPECTED TO GRADUALLY SPREAD
FROM WEST TO EAST ACROSS THE STATE THIS WEEKEND. THE REMNANT
MOISTURE ASSOCIATED WITH THE DISSIPATED FRONT WILL PROVIDE SHOWERS
FOR WINDWARD AREAS.

&&

.AVIATION...
HIGH PRESSURE NORTH OF THE STATE WILL KEEP A MODERATE TO BREEZY
TRADE WIND FLOW IN PLACE THROUGH TUESDAY...WITH CLOUDS AND SHOWERS
FOCUSED PRIMARILY ACROSS WINDWARD AND MAUKA AREAS. MAINLY VFR
CONDITIONS ARE EXPECTED AT THE TERMINALS...BUT BRIEF MVFR CIGS/VSBYS
MAY IMPACT PHLI OR PHTO IN PASSING SHRA.

AIRMET TANGO IS IN EFFECT FOR LOW LEVEL TURBULENCE OVER AND SOUTH
THRU WEST OF THE MOUNTAINS ON ALL ISLANDS. THESE CONDITIONS ARE
EXPECTED TO REMAIN IN PLACE THROUGH THE NIGHT.

AIRMET SIERRA MAY BE NEEDED LATER TONIGHT FOR N THRU E SECTIONS
OF KAUAI DUE TO MOUNTAIN OBSCURATION.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ REMAINS POSTED FOR THE TYPICALLY
WINDY WATERS ADJACENT TO THE ISLANDS OF MAUI COUNTY AND THE BIG
ISLAND...INCLUDING THE KAIWI CHANNEL. SCA CONDITIONS WILL LIKELY
PERSIST THROUGH TUESDAY NIGHT OR WEDNESDAY BEFORE WINDS DECREASE
AND VEER OUT OF THE SOUTHEAST LATER THIS WEEK. THE FORECAST
MODELS APPEAR TO SHOW INCREASING NORTHEASTERLY TRADE WINDS
SPREADING FROM WEST TO EAST OVER THE AREA THIS WEEKEND.

THE CURRENT SMALL...SHORT PERIOD NORTH-NORTHWEST SWELL WILL
GRADUALLY DECLINE THROUGH TUESDAY. A NEW SMALL LONG PERIOD WEST-
NORTHWEST SWELL ARRIVING TUESDAY NIGHT IS EXPECTED TO LINGER
ACROSS THE STATE FROM WEDNESDAY THROUGH FRIDAY. EXPECT A
REINFORCING NORTH-NORTHWEST SWELL THIS WEEKEND. ELSEWHERE...
SOUTH SWELLS WILL MAINTAIN BACKGROUND SURF ALONG SOUTH FACING
SHORES THROUGH MID-WEEK. A LONG PERIOD SOUTH SWELL ARRIVING FRIDAY
IS FORECAST TO PEAK LATE SATURDAY ABOVE THE SEASONAL SOUTH SWELL
AVERAGE...AND THEN SLOWLY SUBSIDE INTO EARLY NEXT WEEK. THE STRONG
TRADE WINDS WILL CONTINUE TO PRODUCE SLIGHTLY ELEVATED CHOPPY
SURF ALONG EAST FACING SHORES THROUGH MID-WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR MAALAEA
BAY...THE WATERS SOUTH OF THE BIG ISLAND AND THE PAILOLO AND
ALENUIHAHA CHANNELS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST TUESDAY FOR THE KAIWI
CHANNEL.

&&

$$

DISCUSSION/MARINE...HOUSTON
AVIATION...JELSEMA



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